The processes of invasion and transcytosis are thought to be necessary steps leading to disseminated infection with Neisseria gonorrhoeae and may be important for causing pelvic inflammatory disease. Previous studies of gonococcal invasion have used human cells in monolayers, but results from these studies are not very consistent with results from studies using fallopian tube organ cultures or tissues from infected patients. Polarized epithelial cells do mimic conditions seen in infection. Therefore, the polarized epithelial cell model will be used to identify proteins necessary for transcytosis by N. gonorrhoeae. Transposon mutagensis will be used to create fusions to alkaline phosphatase in gonococcal genes in order to identify those encoding surface and secreted proteins. Gonococcal mutants with defects in these surface proteins will be screened for inability to transcytose the epithelial cell layer. Transcytosis deficient mutants will be characterized with regard to adherence and invasiveness. Any genes necessary for transcytosis only, will be characterized molecularly. These studies may also reveal whether binding to a host cell receptor is sufficient for invasion and transcytosis.